“Observing quasars is like observing the exhaust fumes of a car from a great distance and then trying to figure out what is going on under the hood.” -Carole Mundell
Have you been tunes in to Starts With A Bang during this past week? The first full week of January brings with it the annual American Astronomical Society’s giant meeting, and some of the most important discoveries and developments of the year! If you missed anything, here’s what we’ve covered:
- Is interstellar travel possible? (for Ask Ethan),
- A distant galaxy cluster reveals the power of Einstein’s gravity (for Mostly Mute Monday),
- The closest star system to us doesn’t have any planets (yet), after all,
- Why are Pluto and Charon so different?,
- Kepler found its longest-period planet ever,
- Why cosmic inflation’s last great prediction may fail, and
- NASA’s Fermi satellite completes map of the sky; reveals unknown monster.
I’ve also, in my time away at the meeting (again, something your support on Patreon helps enable) gotten a number of exclusive interviews and stories about discoveries and upcoming missions, and they’ll be revealed throughout the month on Starts With A Bang! My book, for those of you ordering from Amazon, will be in stock and shipping in just a couple of weeks (you can already download it on Kindle), and if you want it for your class, leave me a note and I can get you/your school/your students 30% discounted educator pricing! And now for the main event: your comments of the week!
From Denier on magnetism and the interstellar medium: “Sorry to rain on everyone’s parade, but the interstellar medium at high speed is nasty. Not only is there intense cosmic ray radiation, but a spacecraft striking random hydrogen atoms at anything over about 0.5c creates more radiation. The level of magnetic shielding needed in that environment would wreak havoc on our biology. It is not just the iron in our blood, but even the water that makes up more than 60% of our bodies is magnetic.”
Sure, a magnetic field of incredible magnitude for a long duration would be necessary at high-speeds in the interstellar medium to prevent collisions with ions; ionizing radiation at high speeds is dangerous and needs to be avoided. So the standard idea is to generate a magnetic field outside the spacecraft and then to shoot any neutral atoms with a laser to ionize them. But, Denier notes, something bad could happen to you, like — for instance — what happens to this frog at the National High Magnetic Field Laboratory in Tallahassee.
As long as you create a more efficient path for the magnetic field lines to travel through the hull of your spacecraft (rather than through the inhabited interior) you won’t have any problems to the humans inside. I am well aware than not all of the problems associated with interstellar travel are easy to solve, but I’m pleased to inform you that this one is!
From Samuel J. Lawson on interstellar travel: “The section on warp drive doesn’t make mention of the proposed Albubierre (sic) drive, of which at last reading Harold White suggested the mass-energy requirement may be only about ~700kg, so long as the solution to the problem of ‘exotic matter’ and controlling the warp bubble from inside (among a great many other problems) are solvable. It may still be impossible (or very, very improbable) and likely requires a reconciliation between general relativity and quantum mechanics which heretofore has not been worked out. There are problems yet-to-be-solved, but at the very least it seems to me that there has been more accomplished in this field than the author suggests.”
If you are listening to what Harold White is suggesting with no evidence and doing anything other than dismissing it with no concern, you are going about this all wrong. (Harold White has said, and continues to say, a lot of garbage without a lot of evidence. If he were an engineer with any other job, no one would pay attention to it; because his job involves testing materials for NASA, he is taken as seriously as the organization of NASA itself. Cut that out.) Everything I mentioned about warp drive is true of the Alcubierre drive; the only difference is that the Alcubierre spacetime is the one known solution to Einstein’s relativity that creates the spacetime conditions necessary for warp drive. No, there has not been more accomplished in this field than I suggest. If you can find a relativist who thinks otherwise, I’ll happily do a 180.
From Eric on quantum computing: “My understanding is that the promise/power of quantum computing has to do with its ability to solve more mathematical problems, faster, than a traditional computer of equivalent power. Another is that entanglement can improve signal compression and encryption over long transmission lines. The fact that the computer will, when all computation in finished, eventually spit out a defined string of 0s and 1s, does not obviate these points. How a quantum computer can do more complex math faster, I’m not sure. Maybe someone else can answer that.”
I am unsure as to how we got onto the topic of quantum computing from a post on a galaxy cluster, but why not, right? Here’s the thing: a traditional computer encodes information into bits: 0 or 1. It has to store them, access them, and manipulate them, and for that, it requires a way to encode them. An abacus uses beads; a disk uses etchings; a solid-state drive (post-2009 flash drive) uses integrated circuit assemblies, etc. That’s traditional computing.
But quantum computing encodes information into qubits, which can use something like a spinning electron to have something encoded into 0, 1, or a superposition of 0-and-1; that special indeterminate state inherent to quantum computing. It’s a way to do probabilistic computing that provides an extra option (and hence, admits for often faster, superior algorithms) than traditional computing. Beyond that, it allows for the theoretical maximum in information storage/manipulation, where a single quantum particle is the “bit”. I hope this helps!
From MobiusKlein on Charon vs. Pluto: “If Charon has no atmosphere to speak of today, does that mean the theft is over? Thus Pluto is on a steady trend to loose it’s current stock of surface volitiles?”
It means that in the war-for-the-volatiles, Charon is definitely the big loser: it lost it all! It doesn’t necessarily mean that Pluto is the big winner though; it’s not like Pluto has all the volatiles now. Instead, there’s a good chance that Pluto had even more volatiles before it coalesced with Charon, but that in the aftermath of them becoming a bound binary, now the outer, higher atmospheric layers are gone.
Pluto’s rate-of-atmospheric loss was much lower than anticipated when we measured it, but the extent of its atmosphere told us it was more tightly bound to Pluto (at lower altitudes, for example) than our models had anticipated. It’s conceivable that without Charon, Pluto would have an even bigger, more diffuse atmosphere than it already does.
In order to find out, we’d need to find a large Kuiper Belt object and view it up close without a giant, near-orbiting moon. Next, please!
From Chris Mannering on large-scale structure: ““•there would be a great cosmic web of structure, with small, medium and large-scale structures clumped together in certain patterns,”
Ethan this is completely untrue. The cosmic web and large scale structure was a complete surprise and shock when technological advances began knocking out data in the late 1980’s.”
This is exactly my area of expertise; this is what my Ph.D. was in, what my research is in, and what my educational sub-focus was in. Although, to be fair, there were only a handful of people working on it quantitatively up through the early 1980s. Fortunately, one of them happened to be my advisor (Jim Fry) and his advisor (Jim Peebles), who wrote the most influential book on the subject up until that point in 1980. Prior to 1980, the argument was where the power would be.
“Bottom-up” proponents like Peebles contended that small imperfections in the cosmic structure would form first, creating clusters, then dwarf galaxies, then large galaxies and finally clusters. “Top-down” proponents like Zel’dovich argues for a pancake/fragmentation model, that saw galaxies forming from larger clusters down to smaller scales. Either way would mean the tilt to the scalar spectral index (n_s) would be large, and so n_s would be far from 1. (Either much smaller or much larger.)
What inflation predicted is that the spectrum of initial fluctuations would be nearly scale-invariant, meaning we’d see a combination of top-down and bottom-up in our Universe for where the large-scale power is, and that n_s would be very close to 1. The current value of 0.968 tells us — from CMB measurements best of all — that this is correct. I don’t know how you think the history of cosmology is different, but I’d love to hear you dig yourself deeper if you’re willing.
No one is pleased about the security breach. Forbes is not unique to this advertising-served malware, but it’s up to them to do something about it. I have contacted them and am awaiting a response.
From Justin on Forbes: “I understand that websites make their money and pay their bills with advertising, and for sites that I trust I have no problem turning adblocker off and looking at their banner ads or what have you, however I do not want to expose my devices to known malware just to read an article (no matter how engrossing it may be).
Is there another site that hosts your full content or is it forbes exclusive now?”
Forbes pays me, so they get the exclusive rights for five full business days. After that, you can read it in full on Medium with no ads. (So, nothing to block.) You have to take the delay, though.
From D.C. Sessions on… surprise… Forbes: “I wanted to read it but Forbes refuses to serve the page, demanding that I turn off the adblocker that I don’t have.”
This is a new one! How weird. What are you running that you’re getting that? If it’s IBM-DOS and Lync… well, I just know there used to be a D.C. Sessions who commented on Starts With A Bang some 7 years ago, but not much since. How ya doin’, buddy?
And finally, for something cool, Michael Kelsey on antimatter galaxies: “@Ethan re Gary S’s question about antimatter galaxies: See http://arxiv.org/abs/1512.08482 for a recent analysis of a slightly more complex “domain wall” analysis, where the authors consider a smooth (Gaussian) density interface between the hypothetical regions.
They first show that this model entirely escapes the best limits on “domain wall” type backgrounds (from COMPTEL, back in the day!). But what I liked is that they go further, and compute the apparent temperature effects from annihilation, and compare that with Planck data. They end up with a ~50 sigma discrepancy vs. data (chi^2 ~ 2400), which is a great exclusion.”
This is a neat paper. Previously, constraints like the one I talked about — domain walls, uniform structure and lack of gamma rays from annihilation — were the strongest constraints. But if one concocts a contrived model to evade those, one can still get an even stronger constraint by looking at the (now amazing) CMB!
You cannot make the Universe we see with equal amounts matter and antimatter, and that’s final!
Here’s looking forward to another great week, and looking forward to seeing you back here for more!